1. Field of the Invention
This invention relates to the hydrometallurgical recovery of copper from chalcopyrite by means of a copper sulfate leaching process.
2. The Prior Art
Processes have long been disclosed describing the recovery of copper from its sulfide and mixed sulfide forms. Most of the economic copper recovery processes are classified as pyrometallurgical, with the ore being smelted to oxidize the sulfide to sulfur dioxide. This sulfur dioxide is now of course recognized as a major air pollutant, and means must be used in conjunction with pyrometallurgical plants to eliminate this contaminant. As a result considerable development is now being undertaken to formulate hydrometallurgical processes in order to circumvent the production of the byproduct sulfur dioxide. Much of the hydrometallurgical development centers around chloride and ammoniacal leaching processes, some of which may prove to ultimately be beneficial.
Copper sulfate leaching agents have been proposed to be used in conjunction with a number of metal sulfides, including zinc sulfide. U.S. Pat. No. 3,655,538 to Renken discloses such a process whereby the zinc sulfide is leached with copper sulfate in order to produce copper sulfide and a zinc sulfate solution, the zinc sulfate solution being easily separated for the ultimate recovery of zinc. Another similar process discloses the utilization of a copper sulfate leach to recover nickel from a nickel-copper matte, this process being set forth by Llanos et al in a paper presented at the Third Annual Meeting of the Hydrometallurgical Section of the Metallurgical Society of C.I.N., Edmonton, Oct. 19, 1973.
Heretofore the value of leaching chalcopyrite with copper sulfate has not been recognized, and it has commonly been believed that chalcopyrite does not react with copper sulfate. This is borne out by the Renken patent, cited above, which specifically sets forth at column 3 that chalcopyrite does not react with copper sulfate.
It has now been recognized that under the proper processing conditions, as hereinafter set forth, copper sulfate can be used as a beneficial leaching agent for chalcopyrite, and such a process results in a number of advantages including providing an effective means for separating copper sulfide from many other metal sulfides and other impurities, as well as greatly facilitating any secondary leaching of the copper sulfides.